The Panopticon was a prison design in which a central tower was surrounded by circles of cells. One guard in the tower could see into all the cells but the prisoners in the cells could not see the guard nor the occupants of the other cells. The prisoners never knew at any particular moment whether or not they were being watched so they had to behave as if they were being watched all the time. They became, in Michel Foucault’s memorable phrase, docile bodies.

The Panopticon has not gone away. Yes, there is surveillance. There is CCTV and GPS - but this is so commonplace now, such a banality, that it does not change our behaviour. Something else is doing that.

The Panopticon has metastasized through towns and cities but with one crucial difference from its original design. There is no central tower. We are all guards and we are all prisoners. We are all watchers and watched. The glass buildings, the open plan offices, the reflective facades, the concourses and the open spaces - every minute of every day we are watching each other through windows, mirrors, reflective surfaces, plate glass, walkways and screens. There is nowhere to hide. Private territory is history: the closed door, the smoky room, the shut curtains, the ‘Knock Before Entering’ sign – they are all gone.